Particle accelerators used in high energy experimental physics employ an array of magnets for accelerating a charged particle to a high velocity. In the quest for higher energies, the magnet arrays have become larger and employ superconducting magnets for the application of even greater magnetic fields to the charged particles. The magnet array is generally in the form of a circle which allows for incrementally increasing the energy of the particles with each transit around the accelerator magnet array. Also in the quest for higher energies, the size of the magnet array has increased to the point where one pass around the accelerator may be as long as several tens of kilometers.
Whenever an accelerator magnet is installed or replaced, the cryogenic pipes between magnets carrying the liquid helium coolant must be welded and certified air tight to reduce the loss of the liquid coolant. Leaks in the coolant containment system allow for escape of the coolant which increases accelerator operating costs and may degrade superconducting magnet performance in accelerating the charged particles.
By far the most time consuming aspect of magnet installation is leak hunting. In a completed machine (i.e., the Tevatron accelerator at Fermilab) there are 1,200 cryogenic interfaces. A typical interface consists of a beam tube seal, several liquid helium and nitrogen connections, and a room temperature insulating vacuum seal. Each of the cryogenic seals must be able to be verified at room temperature with sufficient sensitivity to assure that it will not leak liquid helium. On the average it takes only one-half hour to physically place a magnet, one hour to align it, and four man-hours to complete an interface. However it takes a total of 40 to 50 man-hours to install and leak check each one. A pump out port is supplied on each magnet, near the downstream interface of that magnet. A helium leak detector is put on each one of the four available interfaces and on the beam tube, and the cryostat is pumped down. The first pumpdown on a fresh cryostat typically takes three hours to reach a pressure sufficiently low so that the roughing pumps can be valved off and the leak detector opened fully to the cryostat. When the leak detector is able to be put on its most sensitive scale, leak hunting can proceed.
Previous systems used individual chart recorders to record the results of the leak check process. The scale of current large scale particle accelerators requires a computerized system for recording, analyzing, and documenting the leak check process. Existing commercial systems are not able to meet the requirements of this process.
The present invention addresses the aforementioned problems encountered in high energy particle accelerators employing superconducting magnets by providing a leak checker data logging system and method which allows for computerized monitoring of a plurality of mass spectrometers spaced along the magnet string for detecting, localizing and recording a leak in the superconducting magnet coolant system as well as providing a visual display of system status.